Culture and Sensitivity urine analysis should always be the first route to take, but on the off-chance that there is little or no bacteria evident there is a known condition referred to as 'Idiopathic cystitis'. In the bladder there is a protective layer called a GAG layer. If this is not present then the urine scalds the bladder causing it to bleed. This is treatable with capsules called Cystaid ( N-Acetyl Glucosamine) The dose is one capsule per 2.25KG given daily for 2 to 4 weeks, then maintained on this dose given every other day. [Sukie note: Estelle Jackson is a veterinary nurse in the UK with 14 years of experience. The medication mentioned may not be available in the U.S. Per Bruce Williams there is "a protective layer of glycosaminoglycans which serves to inhibit the attachment of a number of bacteria in the bladder." It is this layer to which she refers.] [Posted in FML issue 3439]